Combustion of powdered fuel



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COMBUSTION OF POWDERED- FUEL Filed April 27, 1923 IZMY JUUCMfd U Patented Apr. $5, lit-'3 t.

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ILLER-E19 EOTHEBY 'WOQD, OF DQNDON, ENGLAND.

COMBUSTIQN OI? BOWDEREID FUEL.

Application filed April 27, 1823. Serial No. 635,044.

To all whom it may concern:

Be it known that I, VVILFRED Ro'rHnnr 'lVoon, a citizen of the United States of America, residing in London, England, have '5 invented certain new and useful. Improve ments Relating to the Combustion of Powdered Fuel, of which the following is a specification.

The method commonly used for burning .10 pulverized fuel in a furnace consists in injecting the fuel into the furnace by means of air which is wholly-or in greater part the air for combustion. Thps the fuel and the air enter the furnace travelling in the same direction. VVhen the whole of the air for combustion does not enter with the fuel, supplementary air is admitted at various parts of the furnace, sometimes at a lower level than the main blast, and this supplementary air is caught by the incoming blast of air and fuel and caused to travel with such blast. The effect of causing the fuel and air to travel in the same direction in this manner is to produce a very long flame requiring a correspondingly long furnace chamber, or, if this length is not provided, impinging on a wall of the furnace which defiects it and The ideal combustion, in which the entire furnace volume is filled with flame, can

hardly be attained. a

To overcome the ill-effect of blowing the fuel into the furnace by means of a considerable portion of the air for combustion, it has been proposed to allow the fuel to fall into the furnace chamber from the top thereof, in the form of a shower; the draught of air ascends the chamber, meeting the descending fuel. So far as the coarser particles of fuel are concerned, the system is good 'because v these descend farthest intothe chamber and meet the freshest err. As, however, the gaseous current has to lee-diverted more or less at right, angles because-the top of the chamber is closed, the finer particles are carried in this direction and the conditions for their combustion are not appreciably improved as compared with those prevailing when the fuel is injected by means of air for combustion. Nevertheless the conditions are more favourable for complete combustion in this proposition than when the fuel is fed With t air int t e and of the fur-- becomes seriously damaged in doing so.

nace tobe met by an ascending draught which then travels horizontally along a I nace that there is substantially uniform combustion over the cross section.

Anyknown device such asa revolving brush or blade wheel may be used for projecting the fuel into the furnace and it may be capable of operating at adjustable speed to afford a control of the distribution of the fuel in the furnace. The feed may be tangential from the wheel.

A feeding apparatus, also controllable as to speed, may be used to regulate the quantity of fuel fed to the brush or wheel.

The accompanying drawing represents diagrammatically a vertical section through a boiler furnace fired in accordance with the invention.

- The combustion chamber 6 of the furnace is preferably in the form of a relatively deep vertical compartment defined by suitable walls of, refractory material having an open top opening into the heating compartment which latter discharges into a fine or stack a.

The furnace flue a draws air into the bottom of the combustion chamber bthrough symmetrically arranged ports 0 controlled by dampers 0!. At the upper part of the front of'the combustion chamber is an inwardly flaring opening e. Registering with this opening is the mouth of a chute 7 through which pulverized fuel is projected by a projector g of the brush type, rotated at variable speed.

The fuel is fed through achute h to a. pulverizer i of any suitable type adapted to reduce the fuel to a size which will pass through a sieve havin say, 30 meshes to the inch; this subdivi ed fuel is conve ed by one or more screw conveyers k to a eed roller Z, the speed of rotation of which may be varied to ensure proper supply of fuel to the projector g. The pulverizer conveying apparatus, feed roller and projecting brush may be operated by any suitable form of gearing that will permit and efiect the proper regulation of the speeds of the several elements.

In carrying out the instant method, the raw coal is fed into the pulverizer i by ineans of the chute it, and the pulverized fuel is taken from the pulverizer by the conveying apparatus is and delivered into the chute f to the feed roller 6 which receives the same and delivers it in accurately regulated amounts and .in properly distrib uted mass to the projector brush 9, which latter is driven at a speed so regulated as to project the pulverized fuel through the opening e, near the top of the combustion chamber F), Where the fuel will assume a shower-like form in the upper part of the combustion chamber and substantially coextensive with the cross section of the latter, thereby efli'ecting a substantial suspension of the fuel with the various particles thereof separated from one another as they tend to fall toward the bottom of the combustion chamber. The dampers (1' being properly adjusted to admit an accurately regulated amount of air to effect complete combustion of the showering fuel particles, the air entering through the openings 0 near the bottom of the combustion chamber flows upward in the combustion chamber in counter-current to the descending fuel particles and is intimately admixed with the latter and effects a complete combustion of the fuel, with the resultant high heat Within the combustion chamber, the resulting products of combustion passing freely out of the open top of the combustion chamber at maximum temperature and under the most favorable condition to produce the desired heating effect in the heating section, before being ultimately discharged through the stack or flue a. It is quite essential to the success of the method that the fuel be so delivered near the top of the combustion chamber that the shower-like effect of the fuel be maintained at all times, so that the individual falling and separated particles of the fuel will come in contact with the counter-current of air as described. It is also necessary that the showering fuel substantially fill the upper portion of the combustion chamber and that the counter-current of air be so regulated as to effect complete combustion Without introducing any unnecessar excess of air which might have the efiect of cooling the products of combustion unduly. The shower-like form of the entering fuel also presents the additional advantage that the heavier particles of fuel travelling through a longer extent of the combustion zone will be acted upon by the combustion supportnastier? ing air for a relatively longer period of time than the lighter particles of the fuel which tend to fall much more slowly through the space in. the combustion chamber and are much more rapidly acted upon by the counter-current of air, so that all of the fuel is subjected to conditions which make for complete combustion of the .fuel Within the combustion chamber proper.

What I claim is:

1. The method of burning pulverized I tlOllWlll be completed Within the chamber; 2. The method of burning pulverized fuel in free suspension in acombustion' chamber having a free outlet near its top, which comprises projecting the fuel latcrally into the chamber near the top thereof to produce a falling shower of fuel in the chamber substantially coextensive with the cross section of the latter, simultaneously introducing a counter-current of air into the lOWCI portion of the chamberfand so regulating the supply of the gravitating fuel shower and the volume of the counter current of air as to insure such relative velocities of the oppositely moving fuel and air that combustion will be completed with in the chamber.

The method of burning pulverized fuel in free suspension in avertically disposed combustion chamber haviuga free outlet at its top, which comprises projecting the fuel into the chamber near the top thereof to produce a shower-like body of fuel in the upper part of the chamber substantially coextensive With the cross section of the latter and tending to fall toward the bottom thereof, introducing a countercurrent of air in the lower part of the chamber, and so regulating the supply of the gravitating fuel shower and the volume of the counter current of air as to insure such relative velocities of the oppositely moving fuel and air that combustion will be completed Within the chamber.

In testimony whereof I have signed my name to this specification.

'WILFRED RO'lHERY WOQD. 

